The present invention concerns washing and dry cleaning apparatus, and particularly concerns dry cleaning apparatus for use with carbon dioxide based dry cleaning systems.
Numerous different apparatus for washing garments and fabrics are known. Examples of patents on washing machines include U.S. Pat. No. 1,358,168 to McCutchen, U.S. Pat. No. 1,455,378 to Allen, U.S. Pat. No. 2,357,909 to Ridge, U.S. Pat. No. 2,816,429 to Kurlancheek, and U.S. Pat. No. 3,444,710 to Gaugler. Such apparatus is, in general, adapted to home use with water-based cleaning systems.
Non-aqueous cleaning apparatus, known as xe2x80x9cdry cleaningxe2x80x9d apparatus, is also known. Dry cleaning employs an organic solvent such as perchloroethylene in place of an aqueous system. Dry cleaning apparatus is not, in general, employed in the home, and is instead situated at a store or central plant. Problems with convention dry-cleaning systems include the toxic nature of the solvents employed.
Carbon dioxide has been suggested as a dry cleaning medium. See, e.g., U.S. Pat. No. 4,012,194 to Maffei. To date, however, a feasible apparatus for carrying out carbon dioxide cleaning has not been provided. One apparatus is described in U.S. Pat. No. 5,467,492 to Chao et al. This apparatus has apparently been supplanted by the apparatus described in U.S. Pat. No. 5,669,251 to Townsend et al. Townsend describes a dry cleaning system having a hydraulically rotated basket that rests on roller bearings. The system is adapted to use with liquid carbon dioxide. Manifolds are disposed between an outer pressure vessel and the basket and have nozzles that produce jets of liquid carbon dioxide that agitate the garments. The basket is said to be rotated by the friction of the garments against the basket walls (column 4, lines 47-48) or by a paddle wheel or turbine (col. 5, lines 8-9). A disadvantage of Townsend is that the basket is supported by roller bearings around the periphery of the basket, which are complex and prevent simple removal of the basket for cleaning, inspection, etc. A further disadvantage is that no practical means of closing and sealing the vessel is disclosed. Since the vessel is pressurized with carbon dioxide, it is critical that any access door be suitably sealed, and it is critical that any loose garments or other materials not inadvertently fall between seal members and leave the door partially unsealed when the vessel is filled with carbon dioxide. A further disadvantage of Townsend is that roller bearings are required between the basket side wall and the side wall of the pressure vessel. Since roller bearings are relatively large, this increases the xe2x80x9cdead spacexe2x80x9d between the side wall of the basket and the side wall of the pressure vessel, which dead space must be filled with liquid that is not operating to clean clothing within the basket.
U.S. Pat. No. 5,267,455 to Dewees et al. describes a dry cleaning system in which carbon dioxide as a cleaning medium is transferred between vessels by means of a second purge gas such as nitrogen. The use of multiple pressurized gases makes the system considerably more complex. The system employs a rotating basket, but a disadvantage is that the basket is rotated by means of a magnet coupling.
Accordingly, there is a continued need for a feasible dry cleaning apparatus that can be used with a carbon dioxide-based cleaning medium.
A first object of the present invention is to provide a cleaning apparatus adapted for use with a carbon dioxide cleaning medium that includes an access door which will not be easily blocked by stray articles of clothing and the like.
A second object of the present invention is to provide a carbon dioxide dry cleaning system that provides a rapid turnover of cleaning fluid to the articles being cleaned.
A third object of the present invention is to provide a cleaning apparatus for use with a carbon dioxide cleaning medium that incorporates a rotating basket without adding bearings or shafts that interfere with either the provision of a suitable access door or the reduction of dead space.
A fourth object of the present invention is to provide a cleaning apparatus for use with a carbon dioxide cleaning medium that incorporates a fluid, or turbine, drive for a rotating basket.
In accordance with the foregoing, a wash tank, or cleaning vessel, adapted for use with a carbon dioxide cleaning medium is provided. The tank has a body member having a front opening formed therein, the body member having side walls and a back wall opposite the front opening. The side walls terminate in a front body member edge portion that defines the front opening. The edge portion serves in the sealing mechanism, as discussed below. A substantially cylindrical basket is disposed within the body member for rotation about a generally horizontal axis. The basket has a front opening formed therein, and has a side wall and a back wall opposite the front opening. The basket side wall terminates in a front basket edge portion defining the basket front opening. The said basket edge portion is spaced forward from the body member edge portion when the basket is positioned in the body member, serving to prevent loose garments or materials placed within the basket from becoming caught in the seal and interfering with seal integrity. A drive mechanism is included to rotate the basket about the axis. A door is hingeably connected to the body member, with the door having a front wall and side walls, and with the side walls terminating in an inner edge portion configured to abut said body member edge portion. The door inner edge portion and the body member edge portion comprise a seal for sealing the door and body member to form an enclosed pressure vessel. A lock mechanism is connected to the body member and configured to sealably connect the body member outer edge portion with the door inner edge portion when the door is in a closed position. A plug is connected to the door, the plug having a surface portion configured to abut the basket front opening when the door is closed, yet permitting rotation of the basket within the body member while preventing items within the said basket from escaping during rotation of said basket.
A problem with prior devices is the need for roller bearings between the basket and the body member. Not only does this increase dead space as discussed above, but roller bearings can be difficult to implement when the basket extends forward of the body member as described above. Accordingly, in a preferred embodiment, an elongate shaft is connected to the basket back wall and coincident with said axis, and a shaft support is connected to the body member back wall. The shaft is disposed in the shaft support to permit rotation of the basket within the body member. This obviates roller bearings between the basket and the body member side wall.
A second aspect of the invention is a method for cleaning articles with a carbon dioxide cleaning medium. The method comprises:
(a) providing a cleaning vessel, the vessel comprising: a body member having an enclosed chamber formed therein; a substantially cylindrical basket disposed within the enclosed chamber for rotation about a generally horizontal axis with the articles to be cleaned contained therein, the basket having a front opening formed therein, the basket having a side wall and a back wall opposite the front opening, the side wall terminating in a front basket edge portion defining the basket front opening; a plurality of blade members connected to the basket back wall; and at least one nozzle (e.g., a single nozzle for each direction of rotation) connected to the body member and configured to direct a stream of liquid carbon dioxide cleaning medium at the blade members to rotate the basket; (b) pumping a stream of liquid carbon dioxide cleaning medium through the at least one nozzle at the blade members to rotate the basket; and (c) draining the liquid carbon dioxide from the enclosed chamber during the pumping step at a rate so that articles in the basket contact both the liquid carbon dioxide cleaning medium and a gas phase while being rotated in the basket. The stream of liquid carbon dioxide cleaning medium is preferably pumped at an amount of 20 to 200 gallons per minute. Preferably, the stream of liquid carbon dioxide cleaning medium is pumped at an amount per minute not greater than twice the volume of the enclosed chamber. In general, the stream of liquid carbon dioxide being pumped at an amount per minute sufficient to impart at least 50 foot-pounds of rotational torque to the basket. Apparatus for carrying out the method is also disclosed.
A third aspect of the present invention is a cleaning apparatus adapted for use with a carbon dioxide cleaning medium, and useful for implementing the foregoing methods and apparatus. The apparatus comprises: a body member having an opening formed therein, the body member having side walls and a back wall opposite the opening, the side walls terminating in a body member edge portion defining the opening; a basket disposed within the body member for rotation about an axis; drive means for rotating the basket about the axis; a door hingeably connected to the body member, the door having a front wall and side walls, with the side walls terminating in an inner edge portion configured to abut the body member edge portion; a lock mechanism connected to the body member and configured to sealably connect the body member outer edge portion with the door inner edge portion when the door is in a closed position to define an enclosed chamber containing the basket; a supply line serving as supply means for supplying a liquid carbon dioxide cleaning medium to the enclosed chamber; drain means for draining a liquid carbon dioxide cleaning medium from the enclosed chamber; and a vent line serving as a vent means for venting carbon dioxide gas from the enclosed chamber while the door is in a closed position, prior to opening the door.
A fourth aspect of the present invention is a method of operating a cleaning apparatus adapted for use with a carbon dioxide cleaning medium. The method comprises the steps of:
providing a working vessel to supply carbon dioxide cleaning medium and a wash tank to receive carbon dioxide cleaning medium, the wash tank including a drain and a rotating basket, the rotating basket containing articles to be cleaned;
partially filling the wash tank by transferring (e.g., by pumping or gravity flow) liquid carbon dioxide cleaning medium from the working vessel to the wash tank to at least partially immerse the articles to be cleaned in the carbon dioxide cleaning medium;
washing the articles by pumping liquid carbon dioxide cleaning medium from the wash tank drain through at least one filter and back into the wash tank as a stream of liquid carbon dioxide cleaning medium, with the basket being rotated by the stream; then
draining the liquid carbon dioxide cleaning medium from the wash tank back to the working vessel so that the articles to be cleaned are no longer immersed in the liquid carbon dioxide cleaning medium; and then
extracting liquid carbon dioxide cleaning medium from the articles by pumping liquid carbon dioxide cleaning medium from the wash tank drain and back into the wash tank as a stream of liquid carbon dioxide cleaning medium, the extracting step being carried out by spinning the basket with the stream.
Gas-phase communication (within the closed system) is provided between the working vessel and the wash tank during the partially filling step, and between the working vessel and the wash tank during the draining step. Preferably, the extracting step is followed by the step of recapturing carbon dioxide gas from the wash tank by transferring (e.g., by compressing, condensing, or combinations thereof) high pressure carbon dioxide gas from the wash tank back to the working vessel. The recapturing step is optionally followed by the step of venting low pressure carbon dioxide gas from the wash tank, after which the wash tank may be opened.
A fifth aspect of the invention system for implementing the foregoing operating method for cleaning articles with a carbon dioxide cleaning medium. The system comprises a working vessel for supplying carbon dioxide cleaning medium; a wash tank for receiving carbon dioxide cleaning medium, the wash tank having a rotating basket disposed therein, the wash tank including a drain; a fill line connecting the working vessel to the wash tank; a pump positioned on the fill line for pumping liquid carbon dioxide cleaning medium from the working vessel to the wash tank; a wash line connecting the pump to the wash tank; a vent line connecting the working vessel to the wash tank; and a drain line connecting the wash tank to the pump.
The foregoing and other objects and advantages of the present invention are explained in detail in the drawings herein and the specification set forth below.